To Port "and Polish" heads... - Ford Muscle Forums : Ford Muscle Cars Tech Forum
FordMuscleForums.com is the premier Ford Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools
Old 11-26-2007, 03:09 PM   #1 (permalink)
Registered User
 
Join Date: Jan 2001
Location: Pullman, WA
Posts: 2,617
Garage
To Port "and Polish" heads...

So we all know that porting is generally a good thing (unless you don't know what you're doing or get carried away). But, once you're done porting the heads, is it really beneficial to "polish" the ports... as in go over them with a fine grit sanding roll to give them a smooth finish?

I've heard that you want to polish the exhaust ports to keep carbon from building up and effectively making your ports smaller, but the intake port you want to leave rough to keep the fuel from sticking to the walls or trickling down into the cylinder. Is this right? And if rough is better for the intake ports, how rough should it be? For instance, if you don't touch a particular part of the port with the grinder, is it best to leave it as-cast, or should it be smoothed slightly with a coarse sanding roll?

I know someone out there has HAD to test before-and-after "polishing" to see if the flowbench sees a benefit, I just want to know what's considered the best thing to do.
__________________
'97 F250HD 4x4 460; '85 Ranger, 350hp 289, T5, 12.9@110.5
"If at first the idea is not absurd, then there is no hope for it. Albert Einstein
Motorhead is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 11-26-2007, 03:38 PM   #2 (permalink)
Registered User
 
Join Date: Nov 2007
Posts: 82
Re: To Port "and Polish" heads...

me too i heard the same thing from a bike mechanic his explanation was the roughnes helps mix the gas and air better as it being sucked in the cylinder and polished on the way out because you dont want it too build up thats what i heard
macrael is offline   Reply With Quote Quick reply to this message
Old 11-26-2007, 03:44 PM   #3 (permalink)
Registered User
 
Join Date: Feb 2001
Location: Indy
Posts: 3,692
Re: To Port "and Polish" heads...

The reason for both is turbulence, you want a little on the way in to promote swirl and keep the fuel atomized and not allow it to drop out of suspension and you don't want it on the way out to promote high velocity.
__________________
07 Victory Vegas Jackpot
93 F150 4.9, AOD(winter beater)
89 5spd Coupe, 351C EFI Spyder, AGS 4 suspension
80 LX 11:1 carb'd 351C w/GForce T5, 17x9 95 R's(daily driver).
1 Bad 88 GT is offline   Reply With Quote Quick reply to this message
Old 11-26-2007, 03:55 PM   #4 (permalink)
Registered User
 
Join Date: Apr 2007
Location: SF Bay Area, CA
Posts: 246
Re: To Port "and Polish" heads...

"Port and polish" is as much of a misnomer as is "balance and blueprint," meaning that if you did not receive a blueprint(s) of every dimension of your engine design and the actual values (of your actual engine) noted along side the called out values on the print, then your engine is not technically blueprinted.

With that in mind, when it comes to the polishing of the ports in the cylinder head, the difference that you will feel in the seat of your pants (hp-wise) is zero (this assumes proper port finishing). For the most part, it simply looks good to the customer. People just seem to like shiny things.

Paul
__________________
http://www.highflowdynamics.com/
paulkane is offline   Reply With Quote Quick reply to this message
Old 11-26-2007, 05:26 PM   #5 (permalink)
Registered User
 
Join Date: Jul 2005
Posts: 1,125
Re: To Port "and Polish" heads...

The point of polishing is to prevent carbon build-up (you do this for the exhaust port) and for the intake, you need it to be rough for a couple of reasons: to keep the fuel atomized and to create more flow since air moves better through a rough surface (to an extent) since the rough surface creates a boundary layer reducing the friction between air and port.
bassman97 is offline   Reply With Quote Quick reply to this message
Old 11-26-2007, 08:36 PM   #6 (permalink)
Registered User
 
Join Date: Sep 2004
Location: Hell Paso,TX.
Posts: 228
Re: To Port "and Polish" heads...

I have "attempted" porting a few sets of heads one pair was from an early 260cid with fair results on a street 302. But I have this memory from my early car days when a I saw a respected "engine guy" finish porting a set of BBC heads for a drag motor. He had done a port and polish job then took what looked like a brake cylinder hone and roughed up the intake ports. Today though I have no idea what a nice cross-hatch pattern does for an intake port but his explanation was basically the same as posted before "keeps the fuel mixed and moving better". But that was 25 years ago, today it's almost cheaper to buy a new set of heads anyway.
CnC heads don't come polished do they? comparing apples to oranges I know. But????
__________________
Bad little Bird
P64falcon is offline   Reply With Quote Quick reply to this message
Old 11-26-2007, 08:47 PM   #7 (permalink)
Registered User
 
Join Date: Apr 2002
Location: Merkel, Tx
Posts: 9,251
Re: To Port "and Polish" heads...

Quote:
Originally Posted by paulkane View Post
"Port and polish" is as much of a misnomer as is "balance and blueprint," meaning that if you did not receive a blueprint(s) of every dimension of your engine design and the actual values (of your actual engine) noted along side the called out values on the print, then your engine is not technically blueprinted.
Blueprinting is laying out a specific set of specifications for the clearances in an engine, based on the intended use of the engine. Parts selection, measurement and machine work is then used to bring everything to the decided specification. It's not necessarily meant as a method to return the engine to whatever dimensions might have been specified on the production prints. You can use published specs as a guide, but they may not be applicable to the end use.
__________________
1967 Falcon 4 door 351C - 70 Mustang 351C
Owner built, owner abused.
ckelly is offline   Reply With Quote Quick reply to this message
Old 11-26-2007, 09:02 PM   #8 (permalink)
Registered User
 
Join Date: Apr 2005
Posts: 865
Re: To Port "and Polish" heads...

When I am building an engine that I want to run REAL good, I always do some touchup work to the ports. This is when I start out with fully CNC ported AFR heads. I can usually pickup from 30 to 60 more HP than the way the come out of the box. I have never seen where leaving a rough surface make more HP than a very smooth one, There MIGHT be something to better gas milege with the rough port finish at part throttle though. You guys are getting max HP mixed up with street driving.

JOE SHERRMAN RACING ENGINES
BIGJOE is offline   Reply With Quote Quick reply to this message
Old 11-28-2007, 01:51 PM   #9 (permalink)
Registered User
 
Join Date: Jul 2007
Location: Hervy Bay Qld Australia
Posts: 60
Re: To Port "and Polish" heads...

Sorry Joe but I don't agree. Polished inlet ports are detrimental to performance and HP. It is best illustraed by golf balls. A smooth golf ball does not travel as far or as fast as a dimpled golf ball. There was also some tests done out here at the Womera Rocket Range with paint finnishes on race cars and it was found a rough finnish added about 5 mph top speed.
gordon is offline   Reply With Quote Quick reply to this message
Old 11-28-2007, 02:20 PM   #10 (permalink)
Registered User
 
Join Date: Aug 2005
Location: Lonsdale MN
Posts: 1,613
Re: To Port "and Polish" heads...

Quote:
Originally Posted by gordon View Post
Sorry Joe but I don't agree. Polished inlet ports are detrimental to performance and HP. It is best illustraed by golf balls. A smooth golf ball does not travel as far or as fast as a dimpled golf ball. There was also some tests done out here at the Womera Rocket Range with paint finnishes on race cars and it was found a rough finnish added about 5 mph top speed.
Thats crazy!!!! not doubting you, just saying its an odd phenomnon. I have heard so many dif things about turbulance and such.

I have heard that you dont want intake ports polished becasue the air goes supersonic and the fuel falls out of suspension.

I have heard you need rough ports to keep the air turbulant and the fuel in suspension.

The whole golf ball dimple thing kinda throws the first one out, becasue a rough port would actually be a little faster.

I dont know what to think!!!!!
sharpshot71 is offline   Reply With Quote Quick reply to this message
Old 11-28-2007, 07:22 PM   #11 (permalink)
Registered User
 
Join Date: Mar 2002
Posts: 63
Re: To Port "and Polish" heads...

I have heard the rough finish/smooth finish thing over and over. What I don't understand is how the gas pooling effect that is supposed to happen with the smooth finish actually happens. Think of it this way. Air is being pumped in and out of the engine at high rates of speed. Too fast for any gas to fall out of suspension within the charge, I would think. The gas is supposed to be atomized as it's introduced. As a cold intake charge enters into an extremely hot combustion chamber, whatever gas that was not atomized upon injection or carbaurtion, should be immediately vaporized. I think the events that occur happen way to fast for gas to convert back into liquid state, especially as it absorbs the heat energy from the combustion chamber. If anyone has real proof it does happen, or can honestly say they've seen dyno proven results, I'd be real interested as I am porting some heads right now.
Cleveland_Rocks is offline   Reply With Quote Quick reply to this message
Old 11-28-2007, 07:31 PM   #12 (permalink)
Registered User
 
Join Date: Jan 2003
Posts: 233
Re: To Port "and Polish" heads...

Those are excellent points, cleveland.
__________________
tjcrawfo is offline   Reply With Quote Quick reply to this message
Old 11-28-2007, 07:40 PM   #13 (permalink)
Registered User
 
Join Date: Apr 2001
Location: Central West Virginia
Posts: 7,019
Re: To Port "and Polish" heads...

Quote:
Originally Posted by gordon View Post
There was also some tests done out here at the Womera Rocket Range with paint finnishes on race cars and it was found a rough finnish added about 5 mph top speed.
I'd have to see some documentation where they got any type of standard race car to gain 5mph by giving it a rough paint job.

Is this something you kind of remembered, or something you can produce some data for?
__________________

66 Mustang, Toploader 4-speed
Pump Gas 306, 10.134@134.71
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
n2omike is offline   Reply With Quote Quick reply to this message
Old 11-28-2007, 08:16 PM   #14 (permalink)
Registered User
 
Join Date: Jul 2005
Posts: 1,125
Re: To Port "and Polish" heads...

The whole rough ports is about boundary layers (something I might take my senior year at college to comprehend more). Basically, the friction between air molecules is much less than the friction between air molecules and some solid surface (Iron or Aluminum for example). What the rough surface on a port does is creates small pockets of air in the rough areas to help reduce the friction of the air going through the ports (similar to dimples on a golf ball). However, there is a limit to how rough you can go. Leaving the ports as casted is too rough and sanding it down w/ 2000 grit is too smooth so there is a fine line. How much will you gain w/ the right roughness, well, someone needs to do some testing on the dyno to find out.
bassman97 is offline   Reply With Quote Quick reply to this message
Old 11-28-2007, 09:34 PM   #15 (permalink)
Registered User
 
Join Date: Jul 2007
Location: Hervy Bay Qld Australia
Posts: 60
Re: To Port "and Polish" heads...

It is worse on a carb engine. The fuel actualy wets the manifold and flows on it in a sheet of liquid. The finnish does not have to be as cast, but not polished, as bassman97 says.
n2omike. It was a special paint by one of the large paint manufacturers which I believe they have patented. It was a V/8 supercar team and they were fined $200,000 for an illegal practice session.
gordon is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Muscle Forums : Ford Muscle Cars Tech Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
MSD distributor cap carbon "button" replacement xcgxl All Ford Techboard 0 11-21-2007 01:56 AM
Don't know what to do "heads" DominickSch All Ford Techboard 19 09-25-2007 05:23 AM
"Victory by Design" on Speed, Ford Muscle series ga289stocker The Garage 0 07-08-2007 09:35 AM
What are "quench heads" Fordota All Ford Techboard 10 06-25-2007 11:51 AM


All times are GMT -7. The time now is 08:55 PM.



Powered by vBulletin® Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Friendly URLs by vBSEO 3.6.0
 

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.